By fast hydraulic binders for mortar or concrete, are meant hydraulic binders with fast setting and hardening. Concretes using such binders in their composition, once they are applied, acquire significant mechanical characteristics in the short term. Preferably they have a compression strength RC of at least one 1 MPa after 4 hours for fluid concrete and of at least 1 MPa after 5 hours for self-placing (or self-compacting) concrete and of at least 12 MPa after 24 hours.
These concretes are fluid or self-placing (or self-compacting) concretes and have a workability duration from a minimum of 1 hour to a maximum of 2 hours.
The workability of fluid concretes is measured by the slump height at the Abrams Cone or—or slump value—(according to the French standard NF P 18-451 of December 1981) and it is estimated that a concrete is fluid when this slump is of at least 150 mm, preferably at least 180 mm.
The workability of self-placing (or self-compacting) concrete is generally measured from slump flow, or spreading, according to the operating procedure described in the document entitled “Specification and Guidelines for Self-Compacting Concrete, EFNARC, February 2002, P19-23”; the value of the spreading is greater than 650 mm for self-compacting concretes (and generally less than 800 mm).